/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.buf;

import java.text.DateFormat;
import java.text.FieldPosition;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

import org.apache.tomcat.util.res.StringManager;

/**
 * Common place for date utils.
 * 
 * @deprecated Will be replaced with a more efficient impl, based on
 *             FastDateFormat, with an API using less objects.
 * @author dac@eng.sun.com
 * @author Jason Hunter [jch@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Costin Manolache
 */
public class DateTool {

	/**
	 * US locale - all HTTP dates are in english
	 */
	private final static Locale LOCALE_US = Locale.US;

	/**
	 * GMT timezone - all HTTP dates are on GMT
	 */
	public final static TimeZone GMT_ZONE = TimeZone.getTimeZone("GMT");

	/**
	 * format for RFC 1123 date string -- "Sun, 06 Nov 1994 08:49:37 GMT"
	 */
	public final static String RFC1123_PATTERN = "EEE, dd MMM yyyy HH:mm:ss z";

	// format for RFC 1036 date string -- "Sunday, 06-Nov-94 08:49:37 GMT"
	public final static String rfc1036Pattern = "EEEEEEEEE, dd-MMM-yy HH:mm:ss z";

	// format for C asctime() date string -- "Sun Nov  6 08:49:37 1994"
	public final static String asctimePattern = "EEE MMM d HH:mm:ss yyyy";

	/**
	 * Pattern used for old cookies
	 */
	private final static String OLD_COOKIE_PATTERN = "EEE, dd-MMM-yyyy HH:mm:ss z";

	/**
	 * DateFormat to be used to format dates. Called from MessageBytes
	 */
	private final static DateFormat rfc1123Format = new SimpleDateFormat(
			RFC1123_PATTERN, LOCALE_US);

	/**
	 * DateFormat to be used to format old netscape cookies Called from
	 * ServerCookie
	 */
	private final static DateFormat oldCookieFormat = new SimpleDateFormat(
			OLD_COOKIE_PATTERN, LOCALE_US);

	private final static DateFormat rfc1036Format = new SimpleDateFormat(
			rfc1036Pattern, LOCALE_US);

	private final static DateFormat asctimeFormat = new SimpleDateFormat(
			asctimePattern, LOCALE_US);

	static {
		rfc1123Format.setTimeZone(GMT_ZONE);
		oldCookieFormat.setTimeZone(GMT_ZONE);
		rfc1036Format.setTimeZone(GMT_ZONE);
		asctimeFormat.setTimeZone(GMT_ZONE);
	}

	private static String rfc1123DS;
	private static long rfc1123Sec;

	private static StringManager sm = StringManager
			.getManager("org.apache.tomcat.util.buf.res");

	// Called from MessageBytes.getTime()
	static long parseDate(MessageBytes value) {
		return parseDate(value.toString());
	}

	// Called from MessageBytes.setTime
	/** 
     */
	public static String format1123(Date d) {
		String dstr = null;
		synchronized (rfc1123Format) {
			dstr = format1123(d, rfc1123Format);
		}
		return dstr;
	}

	public static String format1123(Date d, DateFormat df) {
		long dt = d.getTime() / 1000;
		if ((rfc1123DS != null) && (dt == rfc1123Sec))
			return rfc1123DS;
		rfc1123DS = df.format(d);
		rfc1123Sec = dt;
		return rfc1123DS;
	}

	// Called from ServerCookie
	/** 
     */
	public static void formatOldCookie(Date d, StringBuffer sb, FieldPosition fp) {
		synchronized (oldCookieFormat) {
			oldCookieFormat.format(d, sb, fp);
		}
	}

	// Called from ServerCookie
	public static String formatOldCookie(Date d) {
		String ocf = null;
		synchronized (oldCookieFormat) {
			ocf = oldCookieFormat.format(d);
		}
		return ocf;
	}

	/**
	 * Called from HttpServletRequest.getDateHeader(). Not efficient - but not
	 * very used.
	 */
	public static long parseDate(String dateString) {
		DateFormat[] format = { rfc1123Format, rfc1036Format, asctimeFormat };
		return parseDate(dateString, format);
	}

	public static long parseDate(String dateString, DateFormat[] format) {
		Date date = null;
		for (int i = 0; i < format.length; i++) {
			try {
				date = format[i].parse(dateString);
				return date.getTime();
			} catch (ParseException e) {
			} catch (StringIndexOutOfBoundsException e) {
			}
		}
		String msg = sm.getString("httpDate.pe", dateString);
		throw new IllegalArgumentException(msg);
	}

}
